Gravity and Geoid in Canada
Abstract
The presentation, based upon my involvement over more than four decades with the application of gravity data to some problems of geodesy, consists of two parts: 1. It will show the progress of gravity surveys in Canada based upon the mission mandated by the Dominion Observatory. The surveys started in 1902 with the pendulum measurements, later adding some local Eötvös torsion balance determination and continued from 1945 with the much faster gravity measurements. During the presentation the point distributions, prepared for each decade, and also the relevant data set for the various gravimetric geoid for Canada [1972, 1988, 1995] will be shown. 2. In the 1960s, with the increasing availability of gravity data, the computation of gravimetric deflections and/or geoid determination became a top priority of the Gravity Division of the Observatory. The first computer implementation for gravimetric deflections of the vertical computations were carried out in the early 60s, complemented with terrain corrections computations based on digital elevation data. Parallel to the development of the practical evaluation of the gravimetric geoid, a number of associated problems were also tackled [terrain correction by digital computers, high degree spherical harmonics expansion of surface gravity, various 3-dimensional gravity modeling, etc.]. The first gravimetric geoid for Canada, and the refinements which became possible with the availability of more and more data will be shown and discussed briefly.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2004
- Bibcode:
- 2004AGUSM.G43B..01N
- Keywords:
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- 0920 Gravity methods;
- 1200 GEODESY AND GRAVITY;
- 1219 Local gravity anomalies and crustal structure